OCR 21st Century Science Physics P4 P5 P6 *Unofficial Mark Scheme 2016*

Literally everyone I know found it easy, and I even messed up on the 'easy' questions
Yeah I'm doing triple, but I'm awful at P7 :'(
Do you have any tips?

Can someone explain how you work out the speed question (with the mass and weight), I spent ages on it and ended up guessing 1.8 for some reason

what was question 2)b)ii)?

Something along the lines of "why does spinning the magnet faster make the bulb shine brighter?" or something, I'm not sure

Gravitational potential energy at the top = kinetic energy at the bottom
So whatever numbers we were given (I don't remember them), you had to work out the GPE from them I think, then you also had kinetic energy.
Kinetic energy = 1/2 x mass x velocity². So kinetic energy x 2 = mass x velocity².
You were given the mass, so (kinetic energy x 2) / mass = velocity²
So the answer would have been the square root of (kinetic energy x 2) / mass

That probably made no sense - I can't remember the numbers given, sorry!

Yay that's nice and low - although I've seen it be 33 before...



Aw that's unfortunate stick with your gut feeling!! And yeah I did last year's paper this morning, the one where you had to circle the currents? Yeah I messed that up too.
On the bright side - you never have to learn about them again! (Unless you're doing A Level I guess..lucky me...)
Yeah - I think the 7s are going to be death this year as the others have been relatively nice

And me too! Also I'm awful at Ideas about Science questions and ethics questions too. Just give me science not RE!!



Really? Yay!! How many marks was this one out of? As I did fully correct working...just with the wrong numbers!

Yeah physics boundaries don't fluctuate too much so we shouldn't overestimate the grade boundaries. I personally found it quite easy but thought last years paper was easier and that had 41 for an A*

Wasn't that in the part about the magnet and the motor though, because question 2 was about a lorry and the forces? Or is that just me?

Thank you that's actually really helpful, I worked out the GPE so hopefully I'll get 1 mark ahaha

Yeah physics boundaries don't fluctuate too much so we shouldn't overestimate the grade boundaries. I personally found it quite easy but thought last years paper was easier and that had 41 for an A*

Literally everyone I know found it easy, and I even messed up on the 'easy' questions
Yeah I'm doing triple, but I'm awful at P7 :'(
Do you have any tips?

I think the first 2are wron as you do 5*4= 20
And for the second one I got 10j

Did I read the graph incorrectly because wasn't the average speed 150/20 which is 7.5 m/s?

Thanks so much xoxox you're amazing! I'm so happy you got that 'electromagnetic induction' I put that as a complete guess
For the resistance question, I said to improve she should:
repeat experiment to look for outliers
test more wires
test it on a series circuit
keep the type of wires constant

I also said there was a negative cor/ indirectly prop. I think most people said that. I mentioned other stuff like work done/ energy transferred, but definitely not in great detail

Did I read the graph incorrectly because wasn't the average speed 150/20 which is 7.5 m/s?

1 (a) (i) 22N
(ii) 11 J
(iii) conservation of energy is the idea that energy is never created or destroyed, only transferred or converted. It applies to Roy because his kinetic energy was converted into waste heat energy through conservation.
(b) 5.48 to 2dp - working below
35nx1.5m = 52.5jG.D.P = energy transferred, so 53.5 = 1/2x3.5kgx(velocity)^2Rearrange to get 30 = velocity ^2Velocity = 5.48m/s

2 (a) (i) around 12.5 seconds
(ii) 6.5 m/s
(b) (i) The top tick box, "speed increases, then decreases until the lorry becomes stationary"
(ii) Because it increases the size of the voltage (and therefore current) in the wire.
(c) reaction
(d) Because the forces are acting on different objects. The weight is acting on the road by the lorry and the reaction is acting on the lorry by the road.

3 Car crash seat belt and air bag 6 marker
-in a collision, the car comes to a stop very suddenly
-change in momentum = force x time for which the force acts, therefore as the change in momentum is constant and can't be changed, and as the time is very small, the resultant force is very large
-therefore passengers get injured because there is a large force acting on them, which causes a lot of pressure on the body in a short space of time.
-seat belts are slightly elastic so they stretch slightly. This means that, in a crash, the time taken for the body to stop moving is increased, so the force on the chest is reduced.
-air bags are released. Passengers' heads collide with these instead of the windscreen or dashboard, both of which are hard surfaces. As airbags are soft, they increase the amount of time taken for the passengers' heads to stop moving, so force to the head and neck is reduced.
-by reducing the amount of force, the pressure which the body undergoes is reduced, and so the risk and severity of injury are reduced significantly.

4 Explain how a transformer induces a voltage across the secondary coil: There is an alternating voltage on the primary coil which leads to an alternating current in the coil. This alternating current produces an alternating magnetic field in the iron core which induces an alternating voltage in the secondary coil.

5 (a) Electromagnetic induction
(b) You could have said a few for this one: putting the opposite pole of the magnet in (ie south instead of north), spinning the magnet, taking the magnet out

6 (a) Graph C (the one that looks like a sin graph)
(b) Iron

7 Resistance in parallel wires 6 marker
-the results show a negative correlation, as the number of wires increases, the resistance in the wires decreases
-really need more points as I can't remember mine!!

8 If I remember rightly these were the calculation ones.
(a) (i) 5
(ii) 0.5
(b) (i) 1.5
(ii) 0.2

9 (a) Source C because:
- gamma radiation so it leaves the body quickly
- half life of around 1 hour so the exposure time is quite short and damage is limited
(b) Alpha radiation can't be detected by the badge because it is stopped by all 3 materials so can't pass through any of them.
(c) line drawn from beta to second box down
line drawn from gamma to top box
(d) 4,500,000,000 J
(e) Is this the Eve and Ben question?
(f) He thinks that the perceived risk is higher than the statistical/calculated risk because he has no control over the plant, he doesn't know how it works and so might seem dangerous to him, past nuclear disasters, media and can't see radiation.

10 I think this was the irradiated vegetable 6 marker
-irradiation means being exposed to ionising radiation without coming into direct contact with the source.
-irradiation is used on vegetables to sterilise them - ionising gamma radiation kills all the microbes on the food so it's safe to eat and has a long shelf life (no bacteria exist to grow as mould on it for a while)
-because irradiation doesn't involve contact with the source, the ionising effects stop as soon as the vegetables are removed from the source
-Donna's concerns are unsourced because the food is not radioactive, therefore she cannot become contaminated by eating the vegetables as she is not ingesting radiation
-any more points needed?

? Somewhere in the paper there was the question "how is high level radioactive waste dealt with?" But I don't know where it was: it is stored in glass and steel canisters in water for up to 50 years to cool, before being moved to more permanent storage (burial).

Feel free to add things, or change something you believe is wrong as I am in no way saying that my answers are correct!

I thought I'd make a mark scheme because there have been an annoying lack of them for this board - and I know they're highly sought after. So enjoy!

I'm not sure, like I said I'm not saying my answers are definitely correct!